A 32-year-old woman with poorly controlled diabetes mellitus presents with vaginal candidiasis. She has recurrent episodes despite topical azole therapy. Which investigation is most appropriate to confirm the diagnosis and guide antifungal therapy?

Explanation

## Diagnosis of Candida Vulvovaginitis ### Investigation of Choice **Key Point:** Wet mount microscopy and KOH (potassium hydroxide) preparation is the gold standard first-line investigation for suspected vaginal candidiasis in resource-limited and clinical settings. ### Why This Investigation Works 1. **Immediate visualization**: KOH dissolves cellular material and reveals characteristic budding yeast cells and pseudohyphae 2. **High sensitivity in symptomatic cases**: 40–60% sensitivity when symptoms are present; specificity >90% 3. **Cost-effective and rapid**: Results available within minutes to hours 4. **Practical in outpatient settings**: No need for specialized equipment or culture facilities 5. **Guides empiric therapy**: Positive result confirms candidiasis; negative result warrants alternative diagnosis ### When Culture Is Indicated - Recurrent or refractory candidiasis (to identify species and antifungal susceptibility) - Immunocompromised patients - Atypical presentations **High-Yield:** In clinical practice, symptomatic vulvovaginitis with positive KOH preparation = treat empirically with azoles; no need to wait for culture unless treatment failure occurs. ### Clinical Pearl **Tip:** Always perform both wet mount (for motile trichomonads, clue cells) AND KOH preparation (for yeast) on the same specimen — this covers the three most common vaginal infections simultaneously.